解决方法
这是适用于Rails 2.3.8的代码(行注释使测试不通过)：
test 'cookie testing should work' do
@request.cookies['foo'] = 'Foo'
# cookies['foo'] = 'Foo'
# this does not work to: CGI::Cookie.new('foo','bar')
get :index # does: cookies[:foo] = (cookies['foo'] || "") + " bar!"
# the cookie key in the controller can by a symbol,but not in the test
assert_response :success
assert_not_nil cookies['foo'],"Cookie with foo key should not be nil. Debug: Cookies=#{cookies.inspect}"
assert_equal "Foo bar!",cookies['foo'],"Debug: Cookies=#{cookies.inspect}"
# assert_not_nil @cookies['foo'],"Cookie with foo key should not be nil. Debug: Cookies=#{@cookies.inspect}"
# assert_not_nil @request.cookies['foo'],"Cookie with foo key should not be nil. Debug: Cookies=#{@request.cookies.inspect}"
# assert_equal "Foo bar!",@request.cookies['foo'],"Debug: Cookies=#{@request.cookies.inspect}"
end
我花了很长时间寻找答案.